Contact for PGA and PGA socket

ABSTRACT

A contact  4  for a PGA socket  1  is formed with a plate-like base portion  41 , a pair of projecting portions  42   a   , 42   b  provided continuously at one end of the base portion  41  to extend in a direction substantially equal to the base portion, a turned portion  43  provided continuously at the other end of the base portion  41  to face the base portion  41 , and a tail portion  44  provided continuously at the other end of the base portion  41  not to face the base portion  41 . The turned portion  43  is provided with a contact portion  43   a  contacting a pin of a PGA package on a surface of the turned portion  43  not facing the base portion  41 . This prevents flux from adhering on the contact portion  43   a  of the contact  4  when the contact  4  is soldered on a board.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a contact for PGA and a PGAsocket for connecting a PGA (Pin Grid Array) package provided with aplurality of pins in a grid array fashion to a circuit board substrateand the like.

[0002] A PGA socket includes a base housing formed with contact holes ina grid array fashion, a plurality of contacts located in the contactholes, a cover housing formed with through holes in a grid array fashionwhich the pins of the PGA package can be inserted through, and a slidingmechanism for sliding the cover housing over the base housing. Eachcontact includes a press-fitting portion for press-fitting the contactto be engaged to the base housing, a contact portion for being incontact with a pin of the PGA package, and a soldering portion forsoldering the contact to a printed circuit board and the like. Bysoldering a plurality of contacts on a printed circuit board and thelike, the PGA socket is mounted thereon.

[0003] The pins of the PGA package are inserted into the PGA socketthrough the trough holes of the cover housing by zero insertion force toa position in which the pins of the PGA package face the contactportions of the contacts. The cover housing is slid over the basehousing by the sliding mechanism of the PGA socket and then the pins ofthe PGA package come in contact with the contact portions of thecontacts to be electrically connected therewith. Signals can be therebytransmitted between the PGA package and the printed circuit board andthe like.

[0004] However, upon soldering the soldering portions of the contacts onthe printed circuit board and the like, flux may go into the PGA socketfrom the soldering portions through the gap between the contacts and thebase housing to adhere on the contact portions of the contacts. In sucha case, even if the pins of the PGA package and the contacts arecontacted, a loose electrical connection is arisen that the pins and thecontacts are not electrically connected. For this reason, yield ofproducts containing PGA sockets, printed circuit boards, etc. has beendecreased.

[0005] It is an object of the present invention to provide aconstruction of a contact for PGA that prevents a loose electricalconnection caused by flux adhering on a contact portion of the contactand increases the yield of the products and to provide a PGA socketincluding contacts of the construction.

BRIEF SUMMARY OF INVENTION

[0006] A contact for PGA of the present invention formed by bending ametal plate comprises a plate-like base portion, a projecting portionprovided continuously in the base portion to extend in a directionsubstantially equal to the base portion, a turned portion providedcontinuously at one end of the base portion to face the base portion,and a tail portion provided continuously at the other end of the baseportion not to face the base portion.

[0007] According to the contact for PGA, where the turned portion isused as a contact portion of the contact and a surface of the turnedportion not facing the base portion is used as a contact surface forbeing in contact with a pin of a PGA package, even when the tail portionis soldered on a board and the like, a frequency of adhesion of flux islowered to a great extent since flux may usually move between the baseportion and a surface of the turned portion facing the base portion. Forthis reason, when the above-mentioned contact is used for a PGA socket,a loose electrical connection of the pins and the contacts can beprevented, resulting in increase in yield of the products. The contactfor PGA may be manufactured at low cost since the contact may beobtained by bending the metal plate.

[0008] PGA sockets include PGA sockets used in desktop personalcomputers, micro PGA sockets used in notebook type personal computersand the like.

[0009] The above-mentioned contact for PGA further includes a pair offacing portions provided continuously in the turned portion to extend ina direction substantially perpendicular to a direction connectingbetween the one end of the base portion and the other end of the baseportion add to face each other. According to the contact for PGA, when apair of facing portions is used as contact portions, a pin of a PGApackage and the contact are electrically connected more reliably, sincethe contact and the pin are to be in contact at two points.

[0010] A PGA socket of the present invention comprises theabove-mentioned contacts for PGA, a base housing formed with a largenumber of contact holes for holding the contacts by a press-fit of theprojecting portion in a grid array fashion, a cover housing located tooverlap the base housing and formed with a large number of through holesin a grid array fashion through which the pins of the PGA package forbeing electrically connected with the contacts for PGA can be inserted,and a sliding mechanism for sliding the cover housing over the basehousing.

[0011] According to the PGA socket, each contact used therein has aconstruction where flux is difficult to adhere on the contact portionfor being in contact with the pin of a PGA package. Therefore, a looseelectrical connection caused by flux adhering on the contact portion isnot likely to occur, resulting in increase in yield of the products.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIG. 1 shows an exploded perspective view of a PGA socketaccording to a first embodiment;

[0013]FIG. 2 shows a perspective view of the PGA socket shown in FIG. 1;

[0014]FIG. 3 shows a perspective view of a contact used in the PGAsocket shown in FIG. 1;

[0015]FIG. 4 is an explanatory diagram of the contact shown in FIG. 1;

[0016]FIG. 4(a) is a front view of the contact shown in FIG. 3;

[0017]FIG. 4(b) is a left side elevation view of the contact;

[0018]FIG. 4(c) is a right side elevation view of the contact;

[0019]FIG. 4(d) is a top plan view of the contact;

[0020]FIG. 5 shows a partially sectional view of the PGA socket shown inFIG. 2, taken at line I-I;

[0021]FIG. 5(a) shows pins of a PGA package being inserted;

[0022]FIG. 5(b) shows the contacts and the pins being in contact;

[0023]FIG. 6 is an explanatory diagram of the contacts in the PGA socketshown in FIG. 1 being held by a base housing;

[0024]FIG. 7 is an explanatory diagram of the contacts in the PGA socketshown in FIG. 1 being held by a base housing;

[0025]FIG. 8 shows a variant of the contact shown in FIG. 4;

[0026]FIG. 9 shows a perspective view of a contact used in a PGA socketaccording to a second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Embodiments of the present invention will be described below withreference to the drawings.

A First Embodiment

[0028] A PGA socket according to a first embodiment will be describedbelow with reference to FIGS. 1-7. FIG. 1 schematically shows anexploded perspective view of a PGA socket. FIG. 2 schematically shows aperspective view of a PGA socket. FIGS. 3 and 4 show a contact. FIG. 5shows a partially sectional view of a PGA socket. FIGS. 6 and 7 areexplanatory diagrams of contacts being held by a base housing.

[0029] A PGA socket 1 shown in FIGS. 1 and 2 comprises a base housing 2,a cover housing 3 located to overlap the base housing 2, a plurality ofcontacts 4, an eccentric cam 5 and cam keeping plates 6, 7. The contacts4 are made of conductive material. The base housing 2 and the coverhousing 3 are made of nonconductive material.

[0030] The base housing 2 is formed with a plurality of contact holes 21therethrough between upper and lower surfaces thereof in a grid arrayfashion. However, a part 21 c of the base housing 2 is not formed withthe contact holes 21 for preventing erroneous insertion.

[0031] The contact hole 21 has substantially square-shaped cross sectionand is formed with concave portions 21 a, 21 b on ends of a pair offacing side surfaces (See FIGS. 6 and 7).

[0032] The base housing 2 is provided with projecting portions 22 a, 22b on one side surface and with projecting portions 22 c, 22 d as well onanother side surface facing thereto. The projecting portions 22 a, 22 b,22 c, and 22 d are inserted into below-described opening portions 32 a,32 b, 32 c, and 32 d of the cover housing 3 as shown in FIGS. 2(a) and(b). This prevents the base housing 2 and the cover housing 3 fromeasily detaching.

[0033] Further, the base housing 2 is provided with a substantiallyrectangular parallelepiped projecting portion 23 on a side surface wherethe projecting portions 22 a, 22 b, 22 c, and 22 d are not formed. Theprojecting portion 23 is formed with a slot-like through hole 23 atherethrough between upper and lower surfaces and is provided withconcave portions 23 b, 23 c, which are rectangular in a plan view, inwhich upper and lower surfaces of a region with through hole 23 a formedthereon are included. The cam keeping plates 6, 7 are attached in theconcave portions 23 b, 23 c respectively in a condition where a shaftsection 51 of the eccentric cam 5 is inserted in the through hole 23 a.Thereby the shaft section 51 is held in the through hole 23 a.

[0034] The cover housing 3 has a plurality of substantially circularthrough holes 31 therethrough between upper and lower surfaces thereofin a grid array fashion into which the pins of a PGA package areinserted. However, a part 31 c of the cover housing 3 is not formed withthe through holes 31 for preventing erroneous insertion.

[0035] The through holes 31 are formed in positions in which pins 8 donot contact contacts 4 at insertion into the through holes 31(See FIG.5(a)) and the pins 8 come in contact with contacts 4 when the coverhousing 3 slides over the base housing 2 after insertion (See FIG.5(b)).

[0036] The cover housing 3 is formed with a pair of extending portions34 a, 34 b extending downwardly. The extending portion 34 a also formedwith substantially rectangular opening portions 32 a, 32 b. Theextending portion 34 b is also formed with substantially rectangularopening portions 32 c, 32 d in a similar way. A size of a height(length) direction of the opening portions 32 a, 32 b, 32 c, 32 d issubstantially equal to a size for the projecting portions 22 a, 22 b, 22c, 22 d to be inserted for the purpose of preventing the cover housing 3from wobbling on the base housing 2 in a vertical direction. A size of awidth direction of the opening portions 32 a, 32 b, 32 c, 32 d is widerthan a size of the width direction of the projecting portions 22 a, 22b, 22 c, 22 d so that the pins 8 of the PGA package and the contacts 4may be in contact and out of contact by sliding movement of the coverhousing 3 over the base housing 2.

[0037] Further, the cover housing 3 is provided with a substantiallyrectangular projecting portion 33 on a side surface where the extendingportions 34 a, 34 b are not formed. The projecting portion 33 has aslot-like through hole 33 a therethrough between upper and lowersurfaces. An eccentric portion 53 of the eccentric cam 5 is insertedinto the through hole 33 a.

[0038] As shown in FIGS. 3 and 4, the contact 4 includes a plate-likebase portion 41, a pair of projecting portions 42 a, 42 b providedcontinuously at one end of the base portion 41 to extend in a directionsubstantially equal to the base portion 41, a turned portion 43 providedcontinuously at one end of the base portion 41 to face the base portion41, and a tail portion 44 provided continuously at the other end of thebase portion 41 so that a surface 44 a may be substantiallyperpendicular to a surface of the base portion 41.

[0039] The projecting portions 42 a, 42 b are respectively press-fittedin concave portions 21 a, 21 b in the contact hole 21 formed with thebase housing 2 (See FIGS. 6 and 7). Thereby the contact 4 is held in thebase housing 2. In short, the projecting portions 42 a, 42 b function aspress-fitted portions to the base housing 2.

[0040] The turned portion 43 is bent at obtuse angle so that a contactportion 43 a projecting into opposite side to the base portions 41 isprovided therewith. Therefore, the contact portion 43 a of the turnedportion 43 is elastically deformed by coming in contact with the pin 8of the PGA package (See FIG. 5(b)). In short, the turned portion 43functions as a contact portion for being in contact with the pin 8.

[0041] The tail portion 44 is soldered for the PGA socket 1 to bemounted on a board. In short, the tail portion 44 functions as asoldering portion.

[0042] In the above-mentioned contact 4, usually flux does not adhere ona surface of the contact portion 43 a of the turned portion 43 incontact with a pin of a PGA package (i.e. a contact surface) since fluxpasses from the tail portion 44 over a surface of the base portion 41facing the turned portion 43.

[0043] To adhere on the contact surface of the contact portion 43 aafter passing over the surface of the base portion 41 facing the turnedportion 43, flux is required to rise from the tail portion 44 toboundaries 45 a, 45 b dividing the base portion 41 and the turnedportion 43 through the base portion 41 and then move along the turnedportion 43. Usually, the more flux rises, the more energy is needed.Accordingly, flux is unlikely to reach the boundaries 45 a, 45 b thatare on higher position for the tail portion 44. Therefore, flux isunlikely to adhere on the contact surface of the contact portion 43 a ofthe contact 4.

[0044] The eccentric cam 5 has a sliding function for sliding the coverhousing 3 over the base housing 2. The eccentric cam 5 includes acylindrical shaft section 51, a cylindrical connecting section 52extending from one end surface of the shaft 51 in an axial direction ofthe shaft section 51, and an eccentric section 53 extending from one endsurface of the connection section 52 in an axial direction of theconnection section 52, wherein the shaft section 51 is formed to be inaxial alignment with the connection section 52 and not to be in axialalignment with the eccentric section 53. A rectangular concave portion53 a for fitting an operating tool such as flat blade screwdrivers isformed on the eccentric section 53. The shaft section 51 is insertedinto the through hole 23 a of the base housing 2 and the eccentricsection 53 is inserted into the through hole 33 a of the cover housing3. The eccentric cam 5 is of a height substantially equal to an entireheight of the projecting portion 23 of the base housing 2 and theprojecting portion 33 of the cover housing 3 overlapping each other. Theconnection section 52 is of a height substantially equal to a depth ofthe concave portion 23 b of the projecting portion 23 of the basehousing 2.

[0045] By turning a flat blade screwdriver fitted to the concave portion53 a in direction of arrow a in FIG. 2(a), the cover housing 3 is slidover the base housing 2 in direction of arrow A in FIG. 2(a). By turningthe screwdriver in direction of arrow b in FIG. 2(a), the cover housing3 is slid over the base housing 2 in direction of arrow B in FIG. 2(a).

[0046] The cam keeping board 6 has substantially rectangular form and isof a thickness substantially equal to a depth of the concave portion 23b of the projecting portion 23 of the base housing 2 and provided with ahalf slot-like notch 6 a in a center of one side surface thereof. In aPGA socket 1 in an assembled condition, the cam keeping board 6 islocated in the concave portion 23 b of the base housing 2, so that aside surface thereof facing the side surface with the notch 6 a may beon a base housing 2 side.

[0047] The cam keeping board 7 includes a rectangular side plate 71, anupper plate 72 extending from a top of the side plate 71 in crossdirection, and a lower plate 73 extending from a bottom of the sideplate 71 in a direction equal to the upper plate 72. The upper plate 72is provided with a half slot-like notch 72 a in a center of a sidesurface that is not in succession with the side plate 71. The upperplate 72 is of a thickness substantially equal to a depth of the concaveportion 23 b of the projecting portion 23 of the base housing 2. Thelower plate 73 is of a thickness substantially equal to a depth of theconcave portion 23 c of the projecting portion 23 of the base housing 2.The cam keeping board 7 is mounted on the projecting portion 23 of thebase housing 2 so that the upper and lower plates 72 and 73 may belocated in the concave portions 23 b and 23 c of the base housing 2respectively.

[0048] The connection section 52 of the eccentric cam 5 is located in aslot formed with the notch 6 a of the cam keeping board 6 and the notch72 a of the cam keeping board 7. A size of the slot is smaller than asize of the shaft section 51 of the eccentric cam 5 to prevent theeccentric cam 5 from detaching.

[0049] An assembled condition of PGA socket will be described below.

[0050] The shaft section 51 of the eccentric cam 5 is inserted into thetrough hole 23 a of the projecting portion 23 of the base housing 2. Thecam keeping board 6 is located in the concave portion 23 b of theprojecting portion 23 of the base housing 2. And the cam keeping board 7is mounted on the projecting portion 23 of the base housing 2 so thatthe upper and lower plates 72 and 73 of the cam keeping board 7 may belocated in the concave portions 23 b and 23 c of the projecting portion23 of the base housing 2 respectively. Further, the cover housing 3 ismounted on the base housing 2 so that the base housing 2 may be locatedbetween the extending portions 34a and 34b of the cover housing 3 andthe projecting portions 22 a, 22 b, 22 c, 22 d of the base housing 2 maybe inserted into the opening portions 32 a, 32 b, 32 c, 32 d of thecover housing 3.

[0051] As shown in FIGS. 6 and 7, a plurality of contacts 4 arepress-fitted in the contact holes 21 of the base housing 2 respectively.

[0052] A relationship of positions of contacts 4 and pins 8 will bedescribed below.

[0053] As shown in FIG. 5(a), when a PGA package is mounted on a PGAsocket, pins 8 of a PGA package are inserted through the through holes31 of the cover housing 3 into the contact holes 21 of the base housing2 to a position in which the pins 8 of the PGA package face the turnedportions 43 of the contacts 4 without contacting the cover housing 3 andthe base housing 2.

[0054] When the eccentric cam 5 is turned by flat blade screwdriver indirection of arrow a in FIG. 2(a) in the above-mentioned condition, thecover housing 3 is slid over the base housing 2 in direction of arrow Ain FIG. 2, that is, in direction of arrow C in FIG. 5(a). While thecover housing 3 is being slid, inner walls of the through holes 31thereof come in contact with the pins 8. By being pushed by the coverhousing 3, the pins 8 move in direction of arrow C in FIG. 5(a). Asshown in FIG. 5(b), the pins 8 are hereby in contact with the contactportions 43 a of the turned portions 43 of the contacts 4. At this time,the pins 8 elastically deform the turned portions 43 slightly indirection of the base portion 41 by pressing the contact portions 43 a.Thereby the pins 8 and the contact portions 43 a press each other byelastic restoring force of the turned portion 43.

[0055] In the above-mentioned contact 4 of which construction is shownin FIG. 4, flux rarely adheres on a contact surface of the contactportion 43 a of the turned portion 43 when the tail portion 44 issoldered on a board. The contacts 4, where flux is unlikely to adhere oncontact surfaces of the contact portions 43 a, are used in the PGAsocket 1. Therefore, a loose electrical connection of the pins 8 of thePGA package and the contacts 4 is prevented, resulting in increase inyield of the products. Enlarging the contact 4 in size of the heightdirection to prevent flux from adhering on the contact portion thereofis not necessary, meeting a requirement of thin equipments for mountingPGA sockets. Further, the contact 4 may be manufactured at low costsince the contact 4 may be formed by bending a metal plate.

[0056] Contacts 400, 500, 600 shown in FIG. 8 may be used for the PGAsocket 1 instead of the above-mentioned contact 4. However, the contacts400, 500, 600 shown in FIG. 8 include tail portions in improved shapesof the tail portion 44 of the contact 4. In the contact 400, a tailportion 404 is formed with a valley portion 404 a on a tip portionthereof so that the tail portion 404 may be in U shape. In the contact500, a tail portion 504 is formed with a valley portion 504 a that iswider and shallower than the valley portion 404 a of the tail portion404 of the contact 400, on a tip portion thereof. The contact 600 isformed with two valley portions 604 a, 604 b so that a tip portionthereof may be in wavy shape. When a contact is formed with theabove-mentioned tail portions, an area to be soldered is bigger than thetail portion 44 of the contact 4. As a result, the contact can besoldered on a board more reliably.

A Second Embodiment

[0057] A second embodiment is a variant of the PGA socket according tothe first embodiment, where a contact is deformed. Since the membersdescribed in the first embodiment other than the contact may be appliedto the second embodiment, only a contact of PGA socket will be describedwith reference to FIG. 9 in the second embodiment.

[0058] A contact 9 according to the second embodiment shown in FIG. 9includes a plate-like base portion 91, a pair of projecting portions 92provided continuously at one end of the base portion 91 to extend in adirection substantially equal to the base portion 91, a turned portion93 provided continuously at one end of the base portion 91 to face thebase portion 91, a pair of facing portions 95, 96 provided continuouslyin the turned portion 93 to face each other by extending from both sidesurfaces of the turned portion 93 in the vicinity of a tip portionthereof in a direction substantially perpendicular to a surface of thebase portion 91, and a tail portion 94 provided continuously at theother end of the base portion 91 so that a surface 94 a may besubstantially perpendicular to a surface of the base portion 91.

[0059] Tip portions of the facing portions 95, 96 are bent so that thetip portions of the facing portions 95,96 face in parallel with eachother and so that a distance between the tip portions may be shorterthan a distance between the facing portions 95, 96 in the vicinity ofthe turned portion 93 and slightly shorter than a diameter of a pin of aPGA package. By bending the tip portions of the facing portions 95, 96in this way, contact portions 95 a, 96 a are formed, where the contact 9is in contact with a pin of a PGA package. The contact portions 95 a, 96a are elastically deformed by contacting the pin of the PGA package. Inshort, the contact portions 95 a, 96 a of the facing portions 95, 96function as contact portions contacting the pin of the PGA package.

[0060] The contact according to the second embodiment, similar to thecontact 4 described in the first embodiment, has a construction whereflux is unlikely to adhere on facing surfaces of the contact portions 95a, 96 a for contacting a pin of a PGA package. Further, since thecontact has a construction where the contact 9 and the pin of the PGApackage are in contact on two facing surfaces of the contact portions 95a, 96 a, the contact 9 and the pin are electrically connected morereliably.

[0061] Although the preferred embodiments of the present invention havebeen described, the present invention is not limited thereto. Variouschanges and modifications to the preferred embodiments are possiblewithin the scope of the invention claimed. For example, the contacts 4,9, not being limited to those shown in FIGS. 3 and 9, may include theturned portions 43, 93 having parts to face the base portions 41, 91 andformed continuously at ends of the base portions 41, 91. A slidingmechanism, not being limited to the eccentric cam 5, may be capable ofsliding the cover housing 3 over the base housing 2.

What is claimed is:
 1. A contact for PGA formed by bending a metal platecomprising: a plate-like base portion, a projecting portion providedcontinuously in the base portion to extend in a direction substantiallyequal to the base portion, a turned portion provided continuously at oneend of the base portion to face the base portion, and a tail portionprovided continuously at the other end of the base portion not to facethe base portion.
 2. The contact for PGA according to claim 1, furthercomprising: a pair of facing portions provided continuously in theturned portion to extend in a direction substantially perpendicular to adirection connecting between the one end of the base portion and theother end of the base portion and to face each other.
 3. A PGA socketcomprising: the contacts for PGA according to claim 1; a base housingformed with a large number of contact holes for holding the contacts bya press-fit of the projecting portion in a grid array fashion; a coverhousing located to overlap the base housing and formed with a largenumber of through holes in a grid array fashion through which pins of aPGA package for being electrically connected with the contacts for PGAcan be inserted; and a sliding mechanism for sliding the cover housingover the base housing.
 4. A PGA socket comprising: the contacts for PGAaccording to claim 2; a base housing formed with a large number ofcontact holes for holding the contacts by a press-fit of the projectingportion in a grid array fashion; a cover housing located to overlap thebase housing and formed with a large number of through holes in a gridarray fashion through which pins of a PGA package for being electricallyconnected with the contacts for PGA can be inserted; and a slidingmechanism for sliding the cover housing over the base housing.